Payment fraud is a serious problem in the modern world and the problem is getting worse as more and more payments are made electronically. This applies to online payments in particular where the opportunities for committing payment fraud are rife. One of the most common types of payment fraud is where a user's payment card details are obtained illicitly and used without their authorisation to make purchases online. A significant proportion of card payments worldwide end up being reversed (a so-called “chargeback”) for this reason. Such payments often go through initially because insufficient checks are made to verify the identity of the person using the card details.